KR20150136875A - Power Supply Device - Google Patents

Abstract

According to one embodiment of the present invention, a power supply device includes: a rectifying section which rectifies a commercial alternating current power source inputted from the outside and outputs a directing current power source; a power factor compensating section which compensates a power factor of the directing current power source outputted through the rectifying section; and a rush current blocking section which is disposed between the rectifying section and the power factor compensating section and blocks a rush current initially introduced to the power factor compensating section. The rush current blocking section includes: a ramp voltage generating unit which generates a ramp voltage by using the directing current power source outputted through the rectifying section; and a switching unit which is selectively turned on by the ramp voltage generated through the ramp voltage generating unit and generates an output current.

Description

Power Supply Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply apparatus, and more particularly to a power supply apparatus for supplying power to a light emitting diode.

Due to the growth of the LED lighting market, the efficiency of the LED lighting converters is required to be over 90% in some countries. In a wide area such as a large shopping mall, several modular (switches) Power control is used smoothly.

On the other hand, in order to increase the size of the lighting in recent years, it is necessary to increase the capacity of the capacitor constituting the PFC (Power Factor Correction) and minimize the flickering.

However, capacitance load is increasing in the power supply circuit due to the increase in capacity of the output-stage electrolytic capacitor. This increases the stray current and leads to short-circuit and damage of the modular contact due to the instantaneous overcurrent, thereby causing inconvenience to the user.

Accordingly, the general power supply device has a function of blocking the inrush current generated in the initial charging condition of the capacitor of the backflow improvement circuit.

1 is a diagram showing a power supply apparatus according to the prior art.

Referring to FIG. 1, the power supply apparatus includes a rectifying section 10, a PFC 20, and an inrush current cutoff section 30.

The rectification section 10 includes first to fourth diodes BD1, BD2, BD3, and BD4.

The rectifying unit 10 includes a bridge diode as described above, and converts a commercial AC power (for example, 110 V to 220 V) supplied from the outside into a DC power and outputs the DC power.

The PFC 20 is a power factor correcting unit and compensates the power factor of the DC power converted through the rectifying unit 10 and outputs the corrected power factor.

The PFC 20 includes a step-up function for boosting the DC power and outputting the power as well as compensating the power factor by generating an input current having the same phase as the input voltage, which may be called a step-up converter.

The PFC 20 receives a DC power rectified through the rectifying unit 10 and a switching device Q100, a capacitor C101, and an inductor L100 in order to increase the voltage from the input DC power. .

The diodes D100 and D101 function as reverse flow prevention and bypass functions and the capacitor C100 is a smoothing capacitor that charges the direct current power output through the rectifying section 10 and outputs a smoothed voltage.

An inrush current cut-off portion 30 is disposed between the rectifying portion 10 and the PFC 20. The inrush current cut-off unit 30 is constituted by a NTC thermistor.

The inrush current cut-off unit 30 functions to increase the line impedance, thereby minimizing the damage of the PFC 20 by interrupting the inrush current input to the capacitor of the PFC 20 initially.

The circuit operation characteristics of a general power supply device to which the inrush current cut-off part 30 is not applied are full-wave rectification through the rectifying part 20 when the commercial AC power is applied, and the bypass diode D101 The full-wave rectified DC power is supplied to the capacitor C101 of the PFC 20 and smoothed.

At this time, the output voltage is as follows.

At this time, in the initial condition in which the DC power is charged in the capacitor C101 of the PFC 20, a large current as much as the voltage gradient flows, which is referred to as inrush current.

At this time, the inflow inrush current (ic) is as follows.

Where ic is the inrush current, C is the PFC capacitor C01 and dv / dt is the voltage slope of the PFC capacitor with respect to time.

2, the DC power source rectified through the rectifying unit 20 includes a diode D101, a capacitor C101 of the PFC 20, And the inrush current cut-off portion 30, as shown in Fig.

At this time, an initial inrush current may flow into the capacitor C101 of the PFC 20. Accordingly, the inrush current cutoff unit 30 is connected to the capacitor C101 in series to increase the line impedance, The inrush current flowing into the capacitor C101 is cut off.

That is, the amount of current required for charging the capacitor C101 of the PFC 20 is limited by the line impedance of the NTC of the inrush current cut-off unit 30, and the voltage and current characteristics thereof are as follows.

However, the inrush current cut-off unit 30 as described above has an advantage of using a current limiting part having a component characteristic. However, there is a problem in that efficiency is lowered due to unnecessary conduction loss occurrence, It goes crazy.

On the other hand, the inrush current cut-off unit 30 generates heat over time. That is, in general, when the inrush current cut-off part 30 is applied with NTC of 30 ?, the temperature of the NTC rises to 126 占 as one hour elapses after the operation.

At this time, the factor of reducing the life expectancy of the capacitor due to the rise of the internal temperature of the inrush current blocking portion 30 is expressed as follows.

L is the life expectancy of the capacitor, Lr is the basic service life provided by the manufacturer, Tmax is the maximum guaranteed temperature, and Tc is the temperature of the case with the board.

As described above, the expected lifetime of the capacitor is shown by the value obtained by subtracting Tc from the guaranteed temperature (Tmax) provided by the capacitor. The higher the Tc, the lower the expected lifetime.

3 is a graph showing the correlation between the heat generation of the NTC element of the inrush current cut-off portion 30 and the resistance value variation.

The correlation between the heat generation of the NTC element and the resistance value variation can be expressed by the following relational expression.

y is the NTC heating value, and x is the NTC resistance value.

At this time, in the above relation, when the actual measured value against the heat generation temperature of the NTC is 126 占 폚, the resistance value is 1.89?, And the NTC itself consumes 3.1 W itself.

As a result, power is consumed by the inrush current cut-off unit even in a section in which the inrush current cutoff function is not needed, resulting in a problem that efficiency is lowered.

In the embodiment of the present invention, the inrush current blocking unit is provided to block the inrush current by using a constant resistance value during a period in which the inrush current needs to be interrupted, and to remarkably lower the conduction resistance value in a period in which the inrush current is not required to be interrupted Power supply.

It is to be understood that the technical objectives to be achieved by the embodiments are not limited to the technical matters mentioned above and that other technical subjects not mentioned are apparent to those skilled in the art to which the embodiments proposed from the following description belong, It can be understood.

The power supply device according to an embodiment of the present invention includes: a rectifier for rectifying commercial AC power input from the outside and outputting DC power; A power factor compensator for compensating a power factor of the DC power output through the rectifier; And an inrush current blocking unit disposed between the rectifying unit and the power factor compensating unit to block an inrush current initially flowing into the power factor compensating unit, wherein the inrush current blocking unit rectifies the lamp voltage using the DC power output through the rectifying unit, And a switching unit that is selectively turned on by a ramp voltage generated through the ramp voltage generating unit to generate an output current.

The ramp voltage generating unit includes an R-C time delay unit which is formed of an R-C circuit and generates a ramp voltage gradually increasing with time.

The switching unit may include a first condition for turning off the output current by turning off the lamp voltage, a second condition for gradually increasing the output current by turning on the lamp voltage, And is operated in a third condition that turns on and generates a constant output current.

The first condition is that the ramp voltage is lower than the gate-source threshold voltage of the switching unit, and the second condition is that the ramp voltage is higher than the gate-source threshold voltage of the switching unit, Drain voltage, and the third condition is that the lamp voltage is higher than the gate-drain voltage of the switching unit.

Further, the switching section operates in the ohmic region in the second condition, and operates in the active region in the third condition.

In addition, the switching unit in the ohmic region has a first resistance value, the switching unit in the active region has a second resistance value, and the first resistance value is higher than the second resistance value.

The ramp voltage generating unit may include a noise filter that improves the gate-to-source noise margin of the switching unit in the initial transient characteristics, and a ramp voltage generation unit that minimizes a change in the voltage between the gate and the source of the switching unit, Gt; Zener diode < / RTI >

According to the embodiment of the present invention, by using the active switch which is divided into the section in which the current is blocked, the section in which the current gradually increases and the section in which the constant current flows, the inrush current can be minimized, Thereby maximizing the efficiency due to the low conduction resistance value.

1 is a view showing a power supply device according to the prior art.
2 is a view showing an inrush current inflow path of a power supply device according to the related art.
FIG. 3 is a graph showing a correlation between heat generation and resistance value variation of an NTC element constituting an inrush current cutoff portion according to the related art.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

4 is a view illustrating a power supply apparatus according to an embodiment of the present invention.

4, the power supply includes a rectifier 110, an inrush current interrupter 120, and a PFC 130.

The rectifying unit 110 receives a commercial AC power from the outside, converts it into a DC power by full-wave rectification of the received commercial AC power.

The rectifier 110 may be implemented as a full-bridge diode or a half-bridge diode. In an embodiment, the rectifier 110 may be a full-bridge diode. However, the present invention is not limited to this, and the rectifying part 110 may be implemented by a half bridge diode as well as a full bridge diode.

The PFC 130 is a Power Factor Correction and is disposed at the rear end of the rectifying unit 110 to compensate the power factor of the DC power converted through the rectifying unit 110 and output the compensated power factor.

The PFC 130 has a boosting function for boosting the DC power as well as a function for compensating the power factor by generating an input current having the same phase as the input voltage, which may be referred to as a boost converter.

The PFC 130 receives a DC power rectified through the rectifier 110 and includes a switching device, an inductor coil, and a capacitor for boosting a voltage from the input DC power.

Making the input current of the same phase as the output voltage of the PFC 130 and the input voltage can be achieved by controlling the switching operation of the switching element. The capacitor is a capacitor for a constant voltage output for outputting a constant DC output voltage output through the power factor compensating unit according to a charging voltage thereof.

The inrush current cut-off unit 120 is interposed between the rectification unit 110 and the PFC 130 to block the inrush current initially flowing into the PFC 130 by the rectified power through the rectification unit 110.

The inrush current cut-off unit 120 includes a switching element. The inrush current cut-off unit 120 cuts off the current in the first condition and gradually increases in the second condition according to the operation of the switching device. In the third condition, .

This will be described in more detail below.

5 is a view showing a detailed configuration of the inrush current cutoff unit shown in FIG.

5, the inrush current cut-off unit 120 includes a rectifier 121, a lamp voltage generating unit 122, and a switching unit 123. The inrush current cut-

The rectifier 121 rectifies and outputs the input power.

Further, the rectifier 121 may perform a function of rectifying the input power as well as a function of preventing a reverse voltage.

The lamp voltage generating unit 122 generates the lamp voltage. The ramp voltage generating unit 122 generates a ramp voltage for implementing the turn-on and turn-off of the switching unit 123.

At this time, the lamp voltage generating unit 122 constitutes an R-C time delay circuit, thereby generating an output voltage gradually increasing with time by the R-C.

The switching unit 123 selectively performs a turn-on operation by an output voltage generated through the ramp voltage generating unit 122. [

At this time, the switching unit 123 performs a turn-on operation by a ramp voltage (output voltage) generated through the ramp voltage generating unit 122.

That is, the ramp voltage generated through the ramp voltage generator 122 gradually increases with time due to the R-C time delay circuit.

The lamp voltage generated through the lamp voltage generating unit 122 is applied to the switching unit 123.

At this time, the turn-on state of the switching unit 123 is maintained under the condition that the ramp voltage applied to the switching unit 123 is lower than the gate-source threshold voltage of the switching unit 123, The voltage is not output through the unit 123.

When the ramp voltage applied to the switching unit 123 gradually rises and a ramp voltage higher than the gate-source threshold voltage of the switching unit 123 is applied, the turn-on of the switching unit 123 And a voltage is output through the switching unit 123. FIG.

At this time, a voltage higher than the gate-source threshold voltage is applied to the switching unit 123, but a voltage lower than the gate-drain voltage is applied.

If the ramp voltage output through the ramp voltage generator 122 is greater than the gate-to-source threshold voltage, but lower than the gate-drain voltage, the switching unit 123 operates in the ohmic region. .

At this time, when the switching unit 123 operates in the ohmic region, the resistance value Rds (on) of the switching unit 123 becomes very large.

Accordingly, the operation of the switching unit 123 is performed in the ohmic region from the time when the switching unit 123 is initially turned on until the time when the lamp voltage becomes equal to the gate-drain voltage, The flow of the output current is suppressed as the resistance value of the resistor 123 is considerably large.

Also, when the lamp voltage generated through the ramp voltage generating unit 122 becomes higher than the gate-drain voltage, the switching unit 123 operates in the active area.

At this time, under the condition that the switching unit 123 operates in the active region, the resistance value Rds (on) of the switching unit 123 appears to be very small, so that the conduction loss of the output current does not occur.

Accordingly, the present invention is not limited to the first condition in which the switching unit 123 is turned off, the second condition in which the switching unit 123 is turned on and operates in the ohmic region, So that the inrush current initially flowing into the PFC 130 can be effectively blocked and the conduction loss due to the low resistance value is prevented after the initial condition.

6 is a circuit diagram of the inrush current interruption unit shown in FIG.

Referring to FIG. 6, the inrush current interruption unit will be described in more detail.

The rectifier 121 includes a diode D630.

The lamp voltage generating unit 122 includes a filter unit including a first capacitor C630 and a second capacitor C631 and a first resistor R631, a second resistor R632, and a third capacitor C632 An RC time delay unit, and a Zener diode (ZD630).

The filter unit composed of the first capacitor C630 and the second capacitor C631 is a noise filter and improves the gate-to-source noise immunity of the switching unit 123 in the initial transient characteristics.

The RC time delay unit constituted by the first resistor R631, the second resistor R632 and the third capacitor C632 is connected to a ramp voltage supply unit .

The RC time delay unit causes a rising time delay for a voltage rectified through the rectifier 121 so that the switching unit 123 is supplied with a voltage for turn-on, And a ramp voltage corresponding to the voltage for operation in the active region is generated.

The control diode ZD630 minimizes the gate-to-source voltage change applied to the switching unit 123 according to the input change characteristic changed from 90Vac to 267Vac.

7 is a view illustrating the operation principle of the inrush current cutoff unit according to the embodiment of the present invention.

The graph drawn at the top of FIG. 7 shows the output of the rectifier, the middle plot shows the output of the lamp voltage generator 122, and the graph at the bottom shows the output of the switching unit 123.

And the output voltage is generated by the rectifier 121 at the time T1 when the input power is supplied.

When the output voltage of the rectifier 121 is generated, the rising time of the rising time with respect to the output voltage occurs through the lamp voltage generating unit 122.

The lamp voltage output from the lamp voltage generating unit 122 gradually increases with time.

The switching unit 123 is turned on at a time T2 when the ramp voltage gradually increases and the ramp voltage becomes greater than the gate-source threshold voltage of the switching unit 123. [

When the turn-on operation of the switching unit 123 is performed, an output voltage through the switching unit 123 is generated.

At this time, the ramp voltage generated through the ramp voltage generating unit 122 is larger than the gate-source threshold voltage at the time T2, but is lower than the gate-drain voltage.

Accordingly, the switching unit 123 operates in the ohmic region.

8 is a graph showing the operating characteristics of a switching device included in a rush current blocking unit according to an embodiment of the present invention.

Referring to FIG. 8, the switching unit 123 can be divided into an operating condition in an ohmic region and an operating condition in an active region.

In this case, when the switching unit 123 operates in the ohmic region, the resistance value of the switching unit 123 is very large. When the switching unit 123 operates in the active region, the resistance value of the switching unit 123 is almost (A value close to 0) which does not appear.

Accordingly, the switching unit 123 operates in the ohmic region for a predetermined time at the time when the switching unit 123 is turned on. At this time, since the resistance value of the switching unit 123 is very large, The current is suppressed and the inrush current applied to the PFC 130 is blocked.

When the ramp voltage generated through the ramp voltage generating unit 122 gradually increases and becomes greater than the gate-drain voltage of the switching unit 123, the switching unit 123 operates in the active area So that the output current of the switching unit 123 has a constant value.

At this time, when the switching unit 123 operates in the active area, the resistance value of the switching unit 123 is very low, so that the conduction loss by the switching unit 123 can be minimized.

According to the embodiment of the present invention, by using the active switch which is divided into the section in which the current is blocked, the section in which the current gradually increases and the section in which the constant current flows, the inrush current can be minimized, Thereby maximizing the efficiency due to the low conduction resistance value.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications other than those described above are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

110: rectification part
120: Inrush current cut-
121: rectifier 122: lamp voltage generator
123:
130: PFC

Claims (7)

A rectifying unit for rectifying a commercial AC power input from the outside and outputting a DC power;
A power factor compensator for compensating a power factor of the DC power output through the rectifier;
And an inrush current blocking unit disposed between the rectifying unit and the power factor compensating unit to block an inrush current initially flowing into the power factor compensating unit,
The inrush current cut-
A lamp voltage generator for generating a lamp voltage using a DC power outputted through the rectifying unit,
And a switching unit that is selectively turned on by a ramp voltage generated through the ramp voltage generating unit to generate an output current
Power supply. The method according to claim 1,
Wherein the lamp voltage generating unit comprises:
And an RC time delay unit which is composed of an RC circuit and generates a ramp voltage which gradually increases with time
Power supply. The method according to claim 1,
The switching unit includes:
A first condition for turning off the output current by the lamp voltage,
A second condition that the output current is gradually increased by turning on the lamp voltage,
Operating in a third condition that is turned on by the ramp voltage to generate a constant output current
Power supply. The method of claim 3,
The first condition is that,
The ramp voltage is lower than the gate-source threshold voltage of the switching unit,
The second condition is that,
Wherein the ramp voltage is higher than a gate-source threshold voltage of the switching unit and lower than a gate-drain voltage,
The third condition is that,
Wherein the ramp voltage is higher than a gate-drain voltage of the switching unit
Voltage supply. 5. The method of claim 4,
The switching unit includes:
Operating in an ohmic region in said second condition,
Operating in the active region in the third condition
Voltage supply. 6. The method of claim 5,
Wherein the switching unit in the ohmic region has a first resistance value,
Wherein the switching unit in the active region has a second resistance value,
Wherein the first resistance value is a value
And a second resistance value
Voltage supply. 3. The method of claim 2,
Wherein the lamp voltage generating unit comprises:
A noise filter for improving the gate-to-source noise margin of the switching unit in the initial transient characteristics,
Further comprising a zener diode for minimizing a change in a gate-source voltage of the switching unit in accordance with an input variation characteristic of the commercial AC power supply
Power supply.

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